The efforts to increase the operating speed of the wire drawing process play a crucial role regarding the industrial productivity. The problem is closely related to various features such as heat generation, material plastic deformation, as well as the friction at the wire/die interface. For instance, the introduction of specific lubricants at the interface between the die and the wire may efficiently reduce the friction or in another context, induce a difference in friction among different regimes, as for the case of hydrodynamic lubrication. The present study systematically explores various aspects concerning the drawing process of an electrolytic tough pitch copper wire. To be specific, the drawing speed, drawing force, die temperature, lubricant temperature, and stress distributions are analysed by using experimental as well as numerical approaches. The obtained results demonstrate how the drawing stress and temperature are affected by the variation of the friction coefficient, die geometry, and drawing speed. It is argued that such a study might help in optimizing the operational parameters of the wire drawing process, which further leads to the improvement of the lubrication conditions and product quality while minimizing the energy consumption during the process.

The study of die geometry is vital in determining the surface and mechanical properties of drawn wires, and consequently, their application. In this work, annealed electrolytic copper wire (ETP), with 0.5 mm original diameter was reduced by 19% in dies with 2β = 10º and 18º and Hc = 35 and 50%. The best experimental results were then studied by the Finite Element Method to simulate residual stress distribution. The experimental results show that the friction coefficient decreases as the wire drawing speed increases, and that low 2β and Hc values bring about the most favorable wiredrawing conditions. The simulation shows a variation in the axial and radial tensions, both for the compression and traction stresses on all regions during the wire drawing process. In conclusion, the influence of the internal die geometry on the drawn wire is clarified.

Metalworking is an essential process for the manufacture of machinery and equipment components. The design of the die geometry is an essential aspect of metalworking, and directly affects the resultant product’s quality and cost. As a matter of fact, a comprehensive understanding of the die bearing geometry plays a vital role in the die design process. For the specific case of wire drawing, however, few efforts have been dedicated to the study of the geometry of the bearing zone. In this regard, the present paper involves an attempt to investigate the effects of different geometries of the die bearing. For different forms of reduction as well as bearing zones, measurements are carried out for the wire-drawing process. Subsequently, by extracting the friction coefficients from the electrolytic tough pitch copper wire in cold-drawn essays, the numerical simulations are also implemented. We present the results on both the superficial and center radial tensions obtained by finite element methods. It is observed that the reduction of the friction coefficient leads to an increase in radial stress, while for a given friction coefficient, the substitution of the C-type die by the R-type one results in a decrease in the superficial radial stress of up to 93.27%, but an increase at the center of the material. Moreover, the die angle is found to play a less significant role in the resultant center radial stress, but it significantly affects the superficial radial stress. Lastly, R-type dies result in smaller superficial radial stress, with a change of up to 34.48%, but a slightly larger center radial stress up to 6.55% for different die angles. The implications of the present findings are discussed.

The cold wiredrawing process constitutes a classical-tribological system in which a stationary tribe-element (die) is in contact with a tribe-element in relative motion (wire) and both interacting with the interfacial tribe-element (lubricant). This condition is reflected in the effect of friction as a function of the drawing speed and temperature, and directly affects the wearing of the surface into the die and the final quality on the drawn wire. The aim of this work has been to determine the best conditions to process ETP-copper using two different types of oil/water emulsion lubricants. For this purpose, six different die geometries have been proposed and a set of tests have been carried out at different speeds (between 1 and 21 m/s) to determine those combinations that give a lower value in the required drawing force (F_d). The experiments allowed to know the friction coefficient (µ), the temperature profile inside the drawing die and in the lubricant and also the mean roughness (Ra) in the drawn product. The results have shown that drawing speeds above 10 m/s significantly decrease the drawing force and, as a consequence, the friction effect on the interface. The best results have been achieved in the combinations of the lower die angle (2β = 14°) with drawing speeds between 17 and 18 m/s with both types of lubricants used, obtaining the lower values of the friction coefficient between µ = 0.10–0.15 with the lubricant type D (Agip S234-60 oil at 7% concentration). It has been found that those tests carried out with dies with a smaller approach angle have generally made it possible to obtain better qualities in the final product. Additionally, FEM simulations have been done to analyse those cases with the lower values of µ, throwing values of F_d that are consistent with those measured in the experimental setting and allowing to better understand the behavior of the material as it passes through the die.

Most of the applications of NiTi SMA are as a wire form. In this sense it is important to know the effects of thermo-mechanical processing such as reduction per pass and intermediate annealing on the wire drawing process. For this work they were produced wire by cold drawing using 15 % area reduction per pass with and without intermediate annealing. The starting ingot was produced by VIM process. The influence of thermo-mechanical processing will be related to the martensitic transformation temperatures.